1. Field of the Invention
The present invention generally relates to processing of substrates used in semiconductor, data storage, and allied industries. More particularly, the present invention relates to electronically diagnosing a process, equipment associated with the process, or a processed substrate by creating a signature of the processed substrate in a semiconductor or data storage fabrication (“fab”) facility.
2. Description of the Background Art
The semiconductor, data storage, and allied industries feature manufacturing lines that are rich in data production. Most pieces of fabrication or metrology equipment (“tools”) have a myriad of stored data or generate data that can be collected and stored externally. The stored data may include process conditions within a process tool (e.g., process duration, process temperature, process gas flows, etc.), operating conditions of the process tool (e.g., alarm states, input/output (I/O) signal traces, vacuum and pressure levels, etc.), or general historical data for the process tool (e.g., last preventive maintenance (PM), next PM date, overall uptime, etc.).
In addition, there is also a large quantity of data available from metrology tools. Metrology data may include various substrate feature measurements such as film thickness mapping, resistivity mapping, particle mapping, die-to-database correlations, thickness mapping, resistivity mapping, particle mapping, die-to-database correlations, step height values, line-width measurements, and so on. Metrology data is typically available from both in-situ and ex-situ metrology tools. Metrology tools will frequently also store operating condition data and general historical data.
A process or line engineer can use data from a particular type of tool to evaluate processing trends, view run-rules for a given process, or perform complex statistical calculations. However, to date, this type of analysis has been limited to a particular fab tool.
Statistical techniques for controlling a process are well known in the semiconductor, data storage, and allied industries. For example, statistical process control is “the use of statistical methods to analyze a process or its output to take appropriate actions to achieve and maintain a state of statistical control and continuously improve the process capability” (SEMATECH Dictionary, http://www.sematech.org/public/publications/dict). Such appropriate actions may include monitoring or changing gas flows, temperatures, ramp rates, or the like. Other statistical techniques include using Shewhart charts (e.g., charting a group mean versus standard deviation) for evaluating run-rules according to the well-known Western Electric sensitizing rules published in 1956.
Virtually all process and metrology tool manufacturers produce a software program to view or compare collected data from a particular tool. Additionally, there are third-party software manufacturers that produce software for interfacing with a particular type of tool or type of data. These third-party software programs include AspenTech's Process Explorer; Symphony System's SET; and Brookside's Viewer for display of one or more I/O signal traces; and Triant Technologies Viewer for overlaying alarm flags with I/O data. Symphony System's SET; and Brookside's Viewer can also show trend data. Consequently, these data can be used in controlling a particular tool to optimize a portion of a fabrication process.
Disadvantageously, currently available software can only compare data for a particular type of tool. An equipment supplier typically provides a number of software analysis and comparison programs for use with their own tool or similar tools. However, currently available software is only able to read data from a single tool type.